## SolenoidA long straight coil of wire can be used to generate a nearly uniform magnetic field similar to that of a bar magnet. Such coils, called solenoids, have an enormousnumber of practical applications. The field canbe greatly strengthenedby the addition ofan iron core.Such cores aretypical inelectromagnets.
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## Solenoid Field from Ampere's LawTaking a rectangular path about which to evaluate Ampere's Law such that the length of the side parallel to the solenoid field isL gives a contribution BL inside the coil.The field is essentially perpendicular tothe sides of thepath, giving negligible contribution. If theend is taken so far from the coil that thefield is negligible, thenthe length inside the coilis the dominant contribution.
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## Solenoid Magnetic Field Calculation
The Earth's magnetic field is about half a gauss. The relative permeability of magnetic iron is around 200. Enter data, then click on the quantity you wish to calculate in the active formula above the data entry points. Default values will be entered for unspecified parameters, but the numbers will not be forced to be consistent until you click on the quantity to calculate.
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